System of electrical distribution.



No. 664,|05. Patented Dec. l8, I900.

I C. P. STEINMETZ. SYSTEM OF ELECTRICAL DISTRIBUTION.

(Application filed Feb. 20, 1 900.)

(".0 Model.)

c-pc-pooo Jnventor: CharIesPSteinmetz UNITED STATES PATENT Orinoco CHARLES P. STEINMETZ, OF SCHENECTADY, NE\V YORK, ASSIGNOR TO THE GENERAL ELECTRIC COMPANY, OF NE\V YORK.

SYSTEM OF ELECTRICAL DlSTRlBUTION.

SPECIFICATION forming part of Letters Patent No. 664,105, dated D ember 18, 1900.

Application filed b uary 20, 1900. Serial No, 5,880. (No model.)

To all whom it may concern: translating devices other than the rotary con- Be it known that I, CHARLES P. STEINMETZ, verters. My invention aims to overcome this a citizen of the United States, residing at difficulty by varying the field of the rotary Schenectady, in the county of Schenectady converter or converters in response to varia- 5 and State of NewYork,haveinvented certain tion of the total load on the transmissionnew and useful Improvements in Systems of lines, thereby remedying the imperfect regu- Electrical Distribution, (Case No. 1,602,) oflation which occurs in cases where the field which the following is a description. excitation of the rotary converter is depend- The regulation of rotary converters is nsuent only upon its impressed alternating vol- IO allyet'fected by providing them with fieldtageandits direct-currentload. The specific windings in series with their direct-current means which I employ For effecting the requilnains. As thedirectcurrent load varies, the site variation in field strength of the rotary field excitation of the converter is increased converter or converters is a synchronouslyand causes either a decrease in the amount driven dynamo-electric machine having al- 15 of lagging current flowing into the machine ternat-ing-current terminals and direct-curor an increase in the amount of leading current terminals, the direct-current terminals rent, as the case may be. This advancement being connected in series with the shunt field= in phase of the alternating current decreases winding of the converter or converters, while the drop in voltage in the transmission-lines the alternating-current terminals are con- 20 by which the rotary converter is supplied, nected to a branch leading to the other trans and if these lines possess of themselves suflating devices, the connection being such that ficient inductance or if sufficient. inductance a voltage bearing a direct relation to the load is artificially added the alternating elect-roon such branch circuit is received at the said I motive force at the terminals of the converter alternatingcurrent terminals. The voltage 25 may be maintained constant or caused to rise, at the direct-current terminals of the reguas may be desired. Since the direct-current lating-machine changes in accordance with voltage bears a direct relation to the alterthe shifting in phase and variation in magnatingimpressed electromotive force, the volnitude of the alternating current in the tage on the direct-current mains of the conbranch circuit, thereby varying the field ex- 0 verteristherefore correspondinglyregulated. citation sufficiently to overcome the disturb- Although the converter is provided with ing effects of current in the branch circuit shunt and series field-windings in the same upon the regulation of the system. My inway as ordinary direct-currentmachines, the vention is not, however, in its broader asregulation of the converter, unlike that of pects limited to such a specific arrangement 5 direct-current machines, does not take place of apparatus, but is, on the other hand, of in the converter itself, but in the alternating much broader scope, as will readily be seen transmission-lines leading to the converter. by reference to the claims appended hereto. If in addition to feeding compound-wound ro- A more complete explanation of the inventary converters of the kind mentioned the tion in its details and its mode of operation 4o transmission-lines feed also other translation is to be found in the following description devices or consumption-circuits, then the and the accompanying drawing. amount of current flowing in the transmis- The conductors 1, 2, and 3, leading to the sion-lines is no longer directly dependent primary of the step-down transformerT, are upon the load taken by the rotary converter supposed to represent the receiving end of a 5 or converters. The voltage consumed in the three-phase transmission-line. The current line consequently has no definite relation to from the secondary of the step-down transthe load on the converters, and the regulaformer is supposed to be consumed in a plution of these converters is therefore seriously rality of branch circuits, in one of which is interfered with and becomes imperfect to an placed either a single rotary converter or a extent dependent upon the amount of curnumber of rotary converters in parallel. In rent flowing in the transmission-lines due to the drawings two branch circuits only are shown, one being indicated by the conductors 4L 5 6, leading to a single rotary converter, the other by the conductors 7 8 9, leading to a miscellaneous collection of translating devices. The rotary converter fed from the lines 4, 5, and 6 is of the ordinary type having an armature 10, provided with collector-rings 11 and a commutator12. The converter is compound wound in the ordinary manner, being provided with series windings 15 and shunt-windings 16. The series windings are traversed by the current which flows over the direct-current leads 13 and 14 of the machine to the direct-current mains or bus-bars 17 18. The shunt-windings 16 are connected across the direct-current terminals of the machine, and therefore receive a voltage directly dependent upon the voltage at the alternating-current terminals of the machine. The magnitude of the latter voltage is affected by varying the counter electromotive force of the converter, thereby varying the amount of watt-less current flowing to the converter, and consequently varying the drop in the transmission-lines. If the converter-field is overexcited and the transmission-lines contain sufficient reactauce, then as the load increases the voltage at the alternating-current terminals of the converter may be maintained constant or caused to rise with increase of load in a manner well understood. If the transmission-lines do not happen to contain sufficient reactance, it may be artificially supplied .by means of inductance-coils. In the present instance these may be placed either in the mains 4 5 6, as indicated at 19, or in the secondary leads of the transformer T in such position that all of the secondary current must pass through the inductanc'es before passing to either of the branch circuits 4 5 6 or 7 8 9. The amount of inductance required in the two cases will differ, but the principle of regulation is not affected thereby.

It will be noted that the system so far as described will regulate only for changes of load represented by consumption of energy in the direct-current circuit 13 1a of the converter. If the branch circuit 7 8 9 now begins to supply energy to translating devices, an additional drop of voltage will take place in the transmission-lines 1 2 3. No regulating action of the converter will take place in response to this increase in load on the system except such detrimental incidental effects as may be occasioned by the reduction in voltage at the terminals of the converter. Since the regulating effect of the converter is not called into action in response to variation of load on the transmission-lines, the system therefore is no longer self-regulating, and since the regulation of the converter really takes place by reactions in the transmissionlines and not in the machine itself rigorous automatic regulation of the converter itself therefore disappears. To overcome these difficulties, I provide suitable apparatus for producing a variation in excitation of the converter in response to variation of load on the transmission-lines other than that represented by the energy supplied to the converter itself. The apparatus which I make use of consists of a relatively small regulating dynamo-electric machine somewhat resembling a rotary converter. This machine is provided, like a rotary converter, with a single armature-winding, to which are connected a comm utator and collectorrings. A suitable fieldmagnet structure is provided in cooperative relation to the armature and the excitation of the same can be secured, as desired, in a number of different waysas for example, by means of a shunt-winding across the directcurrent terminals of the machine, or the winding may be supplied with energy from a separate source. In some cases the field may be left entirely unwound, the excitation being obtained in this latter case by means of the reaction of currents flowing in the armaturecircuit. The alternating-curreut terminals of this regulating-machine are connected with the secondary terminals of a transformer placed in series with the mains '7, 8, and 9, through which passes the balance of the energyof the transmission system not consumed by the rotary converter. I have indicated this regulating-machine at 20 and have shown it with its direct-current terminals 21 and 22 connected in series with the shunt field-winding 16 of the rotary converter. The voltage at the terminals 21 and 22 is therefore combined with that impressed upon the winding 16 from the direct;current terminals bearing upon the commutator 12 of the rotary converter, and the excitation of the field of the converter is effected accordingly.

The series transformer, to which the regulating-machine 20 is connected, consists of primary windings 23 in series with the mains 7, 8, and 9 and secondary windings 2-1 in inductive relation thereto. Since the mains 7, S, and 9 represent a three-phase system, the secondaries 2% are connected to correspond, in the present instance a Y connection being used. It is to be understood, however, that a delta connection may likewise be employed, if desired.

The regulating-machine 20, although it resembles in structure a rotary converter, differs radically therefrom in its mode of operation, since it is positively maintained in synchronism with the alternating electromotive force of the mains and its armature prevented from shifting backward or forward in position with respect to its impressed electromotive force as the load on the machine varies. The consequence is that the polar line, due to current flowing in the regulating-machine, is shifted'backward or forward with respect to the field structure in accordance with the shifting-in phase of the current in the secondary 2a of the series transformer. The result is that the voltage at the direct-current terminals of the regulating-machine varies in accordance with the value and phase relation of the current in the mains 7 S 9. The mode of action by which this regulating-machiue is characterized is set forth more atlength in the patent to E.W. Rice, No. 595,412, granted December let, 1897, so that further explanation of the action is deemed unnecessary in the present instance.

A variety of means may be employed for maintaining the regulating-machine 20 in synchronism with the impressed alternating elec tromotive force of the mains. Thus, for ex ample, the machine may be mounted on the shaft of the rotary converter to be regulated or mechanically connected thereto by suitable gearing, or the regulating-machine may be driven by a separate synchronous motor supplied from the mains7 8 9, and this latter is the construction which I have shown in the drawing, the motor being indicated generally by the numeral 25. The synchronous motor 25 and the regulating-machine 20 are shown with their shafts rigidly coupled together; but it will be readily understood that any othersuitablemechanical connection between the machines maybe employed. The directcurrent field of the synchronous motor25 may be excited from any suitable source. In the present instance I have shown the direct-current terminals of the motor connected across the bus-bars or mains 17 and 1S, supplied from the main rotary converter. ArheostatR may be used to regulate the strength of field of the synchronous motor, thereby adjusting the regulating effect of the machine driven thereby. By way of illustration I have shown the branch circuit (indicated by the mains 7, 8, and 9) as supplyinga variety of translating devices, an induction-motor being shown at I, a synchronous motor at S, and a rotary converter at X. The rotary converter last mentioned is connected by its direct-current terminals to a suitable consumption-circuit and may, if desired, supply the current for exciting the field of the synchronous motor S.

Suppose now the load on the mains 17 and 18 were to increase. Then the current flowing through the series coils 15 of the converter supplying these mains would cause an increase in the field strengthof the converter, which increase in field strength will correspondingly increase the counter electromotive force of the machine. If the current in the transmission-lines happened at that time to be lagging, this increase in counter electromotive force would decrease the amount of lagging current, and consequently the drop in the transmission-lines, thereby compensating for the increased drop due to increased load on the converter. If, on the other hand,

the current in the transmission-lines were in phase with or in advance of the electromo tive force, then leading current would flow, which by reacting upon the electromotive force, due to inductance of the transmissionlines, would cause an increase in electromotive force sut'ticient to compensate or more than compensate for the drop in. the lines. The series coil 15 and the inductance 19 are so related as to produce a regulating effect sufficient to take care of variation in load of the converter itself.

The regulatingmachine 20 is arranged to vary the magneto motive force due to the shunt-coils 16 in such a manner as to take care of the drop in voltage occasioned by load on the system other than that on the rotary converter. Supposing a load to be thrown on the branch '7 8 9, then an electromotive force would be impressed upon the alternating-cu rrent terminals of the regulating-machine 20. The regulating-machine would then produce an clectromotive force of a value dependent upon the amount and phase relation of the current flowing, and this electromotive force, being combined in the proper direction with that in the shunt-field circuit of the converter, would cause a variation in field strength of the converter sufficient to compensate for the increased drop in the transmission system.

In the operation of the above-described system it will be observed that the rotary converter in one branch supplies or tends to supply the wattless current flowing in the other branch or branches of the system, so that there is a sort of mutual interchange of wattless currents between the respective branches of the system, whereby there is a tendency to maintain a given phase displacement of current in the transmission-lines.

It will of course be understood that my invention is not limited to the details in construction and operation as above set forth, since it is entitled to a much broader construction.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. The combination of a source of alternating current, a plurality of consumption-circuits leading therefrom, a rotary converter fed from one of said circuits, and means for automatically varying the field excitation of said rotary converter in response to variations of load on more than one of said circuits.

2. The combination of a source of alternating current, transmission-lines leading therefrom, a rotary converter fed thereby, a load of varying power factoralso fed thereby, and means'for automatically varying the field excitation of said rotary converter in response to variation of power factor ofsaid load.

3. The combination of a source of alternating current, a plurality of consumption-circuits leading therefrom, a rotary converter fed from one of said circuits, a translating device or devices fed from another of said circuits, and responsive means for overcoming the varying drop in voltage occasioned by current fiowin g both to said rotary converter and to said translating device or devices.

4. The combination of a source of alternating current, a plurality of consumption-circuits leading therefrom, a rotary converter supplied from one of said circuits, a synchronously-driven dynamo-electric machine having alternating-current terminals and directcurrent terminals, connections between the direct-current terminals and a Winding on said rotary converter, and operative connections between said alternating-current terminals and another of said circuits.

5. The combination of a source of alternating current, a plurality of consumption-circuits leading therefrom, a rotary converter supplied from one of said circuits, a synchronously-driven dynamo-electric machine having alternsiting-current terminals and directcurrent terminals, connections between the direct-current terminals and a winding on said rotary converter, and connections between said alternating-current terminals and the secondary of a transformer the primary of which is in series with another of said circuits.

6. The combination of two branch circuits fed from the same source and arranged to supply energy to translating devices, a phasecontrolling device in one of said branch circuits, and means responsive to current in the other branch circuit for varying the action of said phase-controlling device.

7. The combination of a plurality of branch circuits supplied with alternating currents, and means in one of said circuits for supplying \vattless currents in response to a varying flow of wattless currents in all of said circuits.

S. The combination of a plurality of branch circuits supplied with alternating current, and a phase-controlling means in one of said circuits responsive to the flow of wattless currents in another circuit.

9. The combination of a plurality of circuits supplied with alternating current, and a rotary phase-controlling device in one of said circuits responsive to the How of wattless currents in another of said circuits.

10. The combination of a source of alternating current, transmission lines leading therefrom and connected to a plurality of consumption-circuits, and a rotary converter in one branch circuit arranged to supply watts less current in response to a varying consumption of wattless currents in another branch circuit.

11. The combination of a source of alternating current, transmission -lines leading therefrom and connected to a plurality of consumption-circuits, and a phase-controlling de vice in one of said circuits responsive to the flow of wattless current in another of said circuits.

In witness whereof I have hereunto set my hand this 19th day of February, 1900.

CHARLES P. STEINMETZ. i Vitnesses:

BENJAMIN B. HULL, MABEL E. J AOOBSON. 

